Structure and stability of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>2</mml:mn><mml:msub><mml:mi>H</mml:mi><mml:mi>a</mml:mi></mml:msub><mml:mtext>−</mml:mtext><mml:mi>Mo</mml:mi><mml:msub><mml:mi mathvariant="normal">S</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> at high pressure and low temperatures
Alexander F. Goncharov, Maxim Bykov, Elena Bykova, Konstantin Glazyrin, Vitali B. Prakapenka, Zi-Yu Cao, Xiao‐Jia Chen
Abstract
X-ray synchrotron diffraction (XRD) measurements of single-crystal and powder molybdenum disulfide $\mathrm{Mo}{\mathrm{S}}_{2}$ are performed at pressures (P) up to 78 GPa and temperatures (T) of 20 to 298 K in diamond-anvil cells. The results on single crystals demonstrate a sharp pressure induced isosymmetric phase transition of $2{H}_{c}$ to $2{H}_{a}$ modification at 23 GPa at 40 and 300 K. The structure of the high-pressure $2{H}_{a}$ phase previously inferred theoretically and from powder XRD data is confirmed by our single-crystal XRD data solution, which also definitively determines the atomic potions as a function of pressure. No additional periodicity (commensurate or incommensurate) or distortion is found in the whole P-T range of this study. These results suggest that a previously proposed hypothetic charge-density-wave phase does not host pressure induced superconductivity experimentally found above 90 GPa.